Though Lucier had composed chamber and orchestral works since 1952, the composer and his critics count his 1965 composition Music for Solo Performer as the proper beginning of his compositional career. In that piece, EEG electrodes attached to the performer’s scalp detect bursts of alpha waves generated when the performer achieves a meditative, non-visual brain state. These alpha waves are amplified and the resulting electrical signal is used to vibrate percussion instruments distributed around the performance space. Other important early pieces include Vespers (composition)|Vespers (1968), in which performers use hand-held echolocation devices to locate the approximate physical center of a room, to deepen their understanding of acoustical perception, and to reveal the elements of environmental space through non-visual means.
One of Lucier’s most important and best-known works is I Am Sitting in a Room (1969), in which Lucier records himself narrating a text, and then plays the recording back into the room, re-recording it. The new recording is then played back and re-recorded, and this process is repeated. Since all rooms have a characteristic resonance (e.g., between a large hall and a small room), the effect is that certain frequencies are gradually emphasized as they resonate in the room, until eventually the words become unintelligible, replaced by the pure resonant harmonies and tones of the room itself. The recited text describes this process in action. It begins, “I am sitting in a room, different from the one you are in now. I am recording the sound of my speaking voice…”, and concludes with “I regard this activity not so much as a demonstration of a physical fact, but more as a way to smooth out any irregularities my speech might have,” referring to his own stuttering.